Prosthetic heart valves have been used for many years to treat cardiac valvular disorders. The native heart valves (such as the aortic, pulmonary, and mitral valves) serve critical functions in assuring the forward flow of an adequate supply of blood through the cardiovascular system. These heart valves can be rendered less effective by congenital, inflammatory, or infectious conditions. Such conditions can eventually lead to serious cardiovascular compromise or death.
When a native valve is replaced, surgical implantation of a prosthetic valve typically requires an open-chest surgery during which the heart is stopped and patient placed on cardiopulmonary bypass (a so-called “heart-lung machine”). In one common surgical procedure, an incision is made in the aorta and the diseased native valve leaflets are excised. An array of implant sutures are secured around the periphery of the native valve, and the opposite ends of the sutures are pulled through the incision and then threaded through the sewing ring of the prosthetic valve. The prosthetic valve is then “parachuted” down the array of sutures until it rests against the native annulus. Thereafter, the sutures can be tied off and severed to secure the prosthetic valve to the annulus.
One specific technique that is used to introduce the prosthetic valve into the aorta is referred to as the “shoehorn” technique. In the shoehorn technique, a transverse incision is made in the aortic root, which typically is smaller than the cross-sectional profile of the prosthetic valve. In order to pass the valve through the incision, the valve is inserted into the aortic root at an angle relative to a plane defined by the incision, much like passing a button through a button hole. As can be appreciated, this technique adds complexity to the procedure, can cause laceration of the tissue, and can cause damage to the prosthetic valve.
Another technique used to implant a prosthetic valve involves making an oblique or “hockey stick” shaped incision in the aorta. This type of incision creates a larger opening for the passage of the valve, but is more difficult to close and therefore is more prone to leakage than a straight transverse incision.
Accordingly, there exists a need for new and improved apparatus and methods for introducing a prosthetic valve into the vasculature of a patient.